Various forms of double-walled cartons have been developed of board material to provide inexpensive containers for the economical shipment and storage of fragile articles.
Generally, this type of carton comprises a single sheet of board material which, when folded, produces a smaller box held firmly in spaced relation inside a larger box. Thus, this type of carton performs more or less the same function as a single-walled box with a corrugated sleeve or liner.
Conventional cartons of this general type include means for maintaining the inner and outer walls of the carton in spaced-apart relation. Typically, such means include spacer lugs or tabs at some corners of the carton which extend from the corner score or hinge lines between the panels forming the inner sleeve and engage the inner surface of the outer sleeve. Examples of cartons of this general type are disclosed in U.S. Pat. Nos. 2,513,902; 2,533,070; 2,620,116 and 2,701,088.
Such prior cartons are disadvantaged, however, in that effective spacers are not provided at all four corners of the carton. For example, in the cartons described in the first two patents mentioned above, spacer tabs are not present at the upper right hand corner of those cartons as depicted in their FIG. 5. Consequently, the carton contents can be damaged by impacts against at least ons side of the box, e.g. the right hand side wall of the aforementioned cartons depicted in those two patents. In the carton described in the third of the aforementioned patents, on the other hand, spacer tabs do exist at the four corners of the carton; however, one set of those tabs is movable toward and away from the outer wall. Therefore, they do not provide sufficient buffering against hard impacts on that outer wall of the carton.
Also, it would be desirable if a double-walled carton of this general type could have effective interior shock absorbing partitions so that a plurality of fragile articles contained in the carton can be isolated from one another. There do exist double-walled cartons having a single layer partition; however, they do not constitute adequate shock absorbers between the adjacent articles in the carton in all applications. Moreover, such prior partitioned double-walled cartons still do not have spacers between the inner and outer carton walls at all four corners of the carton.